For the last several weeks, I have been responding to biologist Dennis Venema’s criticisms of the RTB human origins model. (Go here, here, and here to read my previous responses.) Venema’s critique has centered on our views on the genetic similarity between humans and chimpanzees.
As part of our assessment of human evolution, we at RTB question whether there is as strong a genetic connection between humans and chimps as is commonly communicated to the general public. Most people are familiar with the claim that humans and chimps share a 99 percent DNA similarity. Our assertion, however, is that the genetic commonality between these two primates is closer to 90 percent.
We also maintain that “percent genetic comparisons” have no biological meaning. In fact, we believe that the emphasis on percent genetic similarity actually hinders our comprehension of the genetic basis for the biological and behavioral differences between humans and chimpanzees, which, as Hugh Ross and I discuss in Who Was Adam?, scientists are beginning to understand. These differences have little to do with which genes are present in the human and chimpanzee genomes or the similarity of their DNA sequences. Instead, these two species’ biological and behavioral distinctions stem from differences in gene expression. (Gene expression describes which genes are used in a particular tissue and at a particular time during the course of growth and development.)
I’ve also discussed the human-chimp genetic differences in several articles on our website.
- “Humans and Chimps Differ”
- “Yet Another Genetic Difference between Humans and Chimpanzees”
- “New Brain Study Spoils Evolutionary Drama”
When using gene expression as a barometer, there is a significant and meaningful genetic difference between humans and chimpanzees. And when it comes to discussing the validity of human evolution, the focus should be on whether or not changes in gene expression patterns can take place in a coherent manner through time in such a way as to account for the emergence of human beings from an ancestral ape-like creature. In my view, percent genetic similarity really has no place in the discussion.